JWM (Joe's Window Manager) is the default window manager in many Puppy Linux versions including Puppy4. It is light weight using only Xlib at a minimum.

A window manager is an application that manages windows: it lets you open, close, maximize and minimize windows. The window manager draws the window borders and captions.

In order to keep Puppy small in size and retain functionality, Puppy uses a lightweight window manager called JWM (Joe's Window Manager), which also manages a panel on the bottom of the screen. Some versions of Puppy contain other window managers, such as IceWM, Fluxbox or Openbox.